Most of the whole blood collected from donors today is not itself stored and used for transfusion. Instead, the whole blood is separated into its clinically proven components (typically red blood cells, platelets, and plasma), which are themselves individually stored and used to treat a multiplicity of specific conditions and diseased states. For example, the red blood cell component is used to treat anemia; the concentrated platelet component is used to control thrombocytopenic bleeding; and the platelet-poor plasma component is used as a volume expander or as a source of Clotting Factor VIII for the treatment of hemophilia.
Plastic bags have met widespread use and acceptance for collecting, processing and storing these blood components.
In collecting whole blood components for transfusion, it is desirable to minimize the presence of impurities or other materials that may cause undesired side effects in the recipient. For example, because of possible febrile reactions, it is generally considered desirable to transfuse red blood cells substantially free of leukocytes, particularly for recipients who undergo frequent transfusions.
One way to remove leukocytes is by washing the red blood cells with saline. This technique is time consuming and inefficient, as it can reduce the number of red blood cells available for transfusion.
Another way to remove leukocytes is by filtration. Systems and methods for accomplishing this in conventional blood bag systems are described in Wisdom U.S. Pat. Nos. 4,596,657 and 4,767,541, as well as in Carmen et al U.S. Pat. Nos. 4,810,378 and 4,855,063. Other systems and methods for removing leukocytes in the blood bag systems are described in Stewart U.S. Pat. No. 4,997,577 and Stewart et al. U.S. Pat. No. 5,128,048. In these arrangements, an in line filtration device is used.
A need still exists for further improved systems and methods for removing undesired matter like leukocytes from blood components before transfusion or storage.